Baby corals are appearing in Maldive Island reefs devastated by coral bleaching 15 years ago, offering hope of recovery, Scripps graduate student Jill Harris found on a trip to the Indian Ocean archipelago in July.

The Maldives were hard hit by a 1998 coral bleaching episode that wiped out many reefs in the Indian Ocean and elsewhere. Bleaching occurs when unusually warm water causes coral to swiftly expel the algae living in its tissue.

Although the bleaching occurs over days or weeks, the damage persists for decades or longer. Off the Lhaviyani Atoll in the Maldives, Harris and fellow Scripps Institution of Oceanography graduate student Levi Lewis saw the aftermath firsthand.

“Swimming around an area the size of several football fields, we would see hundreds of these huge ghost coral colonies,” Harris wrote in a blog post on the expedition.

Centuries old reefs were structurally intact but completely dead, she wrote.

“It’s dramatic and sad to see this organism that’s been around for centuries die off in weeks,” she said.

But there were also hints of hope, with small colonies of young, live coral emerging on the ghost reefs. Those growths suggested that some coral species are re-colonizing the area, she said.

A tiny sea star on the reef at Lhaviyani Atoll in the Maldives. Photo by Jill Harris

A tiny sea star on the reef at Lhaviyani Atoll in the Maldives. Photo by Jill Harris

“We saw this little recruitment garden of juvenile corals that looks like they all started to grow at the same time,” she said.

Moreover, while some sections of coral were obliterated, others were barely affected. They still displayed the diversity and abundance of healthy, mature reefs, she said. The finding was a relief, she said.

“If all you see is devastation and nothing’s getting better, it becomes a really depressing thing to study,” she said.

After their month-long expedition to the islands, Harris and Lewis plan to spend months in the lab analyzing their findings. With little documentation of the original bleaching event, they’ll have to reconstruct the conditions that led some corals to collapse.

“We have to be historical scientists a little bit and figure out what happened,” she said.